This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented or described. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:    3GPP third generation partnership project    AU allocation unit    DL downlink (eNB towards UE)    eNB EUTRAN Node B (evolved Node B)    EPC evolved packet core    EUTRAN evolved UTRAN (LTE)    FDD frequency division duplex    FDMA frequency division multiple access    LTE long term evolution    LTE-A LTE advanced    MAC medium access control    MM/MME mobility management/mobility management entity    Node B base station    OFDMA orthogonal frequency division multiple access    O&M operations and maintenance    PDCCH physical downlink control channel    PDCP packet data convergence protocol    PHY physical    QoS quality of service    RLC radio link control    RRC radio resource control    S-GW serving gateway    SC-FDMA single carrier, frequency division multiple access    TDD time division duplex    UE user equipment    UL uplink (UE towards eNB)    UTRAN universal terrestrial radio access network    VoIP voice over internet protocol
As employed herein LTE/IMT-A indicates LTE on longer time scale (e.g., Release 10 and beyond, including FSU and interference management capabilities).
As employed herein WLAN indicates an IEEE 802.11 type radio system that implements a contention-based sharing mechanism for radio resources.
The use of unlicensed radio bands has facilitated the implementation of WLAN and other important types of wireless communication systems. However, due to a lack of rules and regulations regarding the sharing of common radio resources these systems may not operate at their full potential, and furthermore implementations of these systems may suffer from an inability to be effectively scaled.
Regulatory authorities have recognized the usefulness of unlicensed bands, and may agree on, new spectrum allocations for unlicensed use. However, simply providing additional spectrum does not solve the basic problem related to cooperative sharing of the spectrum between the users of the radio resources.
The concept of “cognitive radio” has been proposed/developed at least partially in response to these problems. For example, a considerable amount of effort in cognitive radio development has been directed to achieving non-interfering coexistence with “legacy systems”, such as existing cellular wireless communication systems. If it were possible to share radio bands With existing non-cognitive systems then more spectrum could be made available. However, in regards to the allocation of future-license-free radio bands a different set of problems arise that require unique solutions (e.g., solutions that may be less efficient and more complicated than the use of a band reserved for FSU-enabled radios).
There is common agreement that fixed radio resource allocations, as commonly used in current wireless communication systems, are inefficient. The majority of all radio spectrum in a given physical location is effectively unused and could be utilized without both causing or suffering intolerable interference.
The authorities in charge of spectrum allocations (typically government agencies) have recognized the potential of a more flexible spectrum access, and are working towards deregulating access to at least part of the radio spectrum. Key enablers for the implementation of new spectrum sharing methods include progress in digital technology and the trend towards the use of wider bandwidths.
Significant research effort has been invested in the context of “cognitive radio” on enabling next-generation radio devices to share spectrum used by an existing system. The cognitive radio would operate to attempt to sense the presence of existing users of a radio resource (primary users), and to determine whether it is possible to reuse the spectrum without causing intolerable interference to the primary user. This task may be very difficult to accomplish since in most cases it is only possible to sense the presence of a transmitter, whereas interference occurs at a receiver that cannot be directly sensed. This is known as a “hidden-node problem”. For example, the operators of fixed satellite services assert that sharing satellite bands is not possible. Certain critical problems need to be solved first, both of a technical and a political nature, and “flexible spectrum use” (FSU) in such bands is a long-term target.
There is a clear need for frequency allocation. Currently, the ISM bands, for example WLAN, are heavily used and relied upon. But radio systems in these bands do not scale to high user densities, as for example in a case where there may be a large number of personal wireless devices with wireless broadband connectivity. While the openness of the ISM bands was a key contributor to the success of WLAN, it can be clearly seen now that it is limiting the scalability.
It is expected that spectrum regulation authorities will meet the demands for growing wireless broadband connectivity by allocating new radio spectrum in the low GHz range. These allocations may abandon the conventional and inefficient exclusive grant of one radio resource to a single operator. If this is the case, then there will be needed some means of coordination between devices to share the radio resources in a fair and efficient manner.